Vitamin C wears a couple of different hats when it comes to keeping you healthy. It’s used to grow, maintain and repair tissues that make up your skin, tendons, ligaments, blood vessels, cartilage, bones and teeth (and more). Vitamin C is especially important for the production of collagen, the component in your skin that keeps it firm. It’s also a potent antioxidant—a nutrient that neutralizes the activity of free radicals, harmful compounds that, over time, can cause your cells to age and potentially contribute to concerns like arthritis, heart disease and cancer.

Although vitamin C is a popular remedy for the common cold, research on its efficacy is ongoing and conflicting. Scientists are also currently studying whether vitamin C protects against cancers of the stomach and esophagus, as well as cervical dysplasia, cardiovascular disease and cataracts.

How much vitamin C do you need?

The recommended dietary allowance (RDA) of vitamin C for adults is 90 mg for men and 75 mg for women. This amount is considered enough to provide adequate antioxidant protection. Most Americans easily get enough vitamin C to protect against a deficiency called scurvy, which causes defects in the body’s connective tissues.

Smokers need an extra 35 mg a day, since their habit may diminish levels of the vitamin. It’s unclear whether you need a higher dose if you are regularly around secondhand smoke, but it is especially important that you get your RDA.

Some people over 65 may benefit from higher doses of vitamin C, too. The reason is two-fold: Vitamin C deficiency is more common in older adults, and the nutrient may protect against chronic diseases that are associated with aging, such as stroke and others already mentioned. If you fall into this age group, talk to your doctor to see if you could benefit from a diet higher in vitamin C or if you should consider taking supplements.

Where can you get vitamin C?

Most of the vitamin C in our diets comes from fruits and vegetables. Cooking reduces the amount of the nutrient in foods, so be sure to include some raw produce in your diet. Vitamin C helps your body absorb iron, so try combining foods that contain both of them in the same meal if you need to increase your iron levels. Some of our favorite foods that contain substantial amounts of vitamin C:

Although the jury is out on the immune benefits of this nutrient, there’s little harm in taking vitamin C supplements to try to prevent or treat a cold. Any immune benefits likely come with large doses. Stick with no more than two daily doses of 500 mg each—that’s all that your body can absorb at one time. Look for “buffered” vitamin C supplements to prevent digestive irritation.